FORMING NOUN PLURALS (1) (Notes)
To show joint ownership, add the possessive form to the second noun only.
my aunt and uncle's house
In compounds, make only the last word possessive.
my father-in-law's car
If a word does not end in s, add 's to form the possessive whether the word is singular or plural.
the actor's part
If the plural of a word ends in s, add only the apostrophe to form the possessive.
the two girls' chairs
Names ending in y form their plurals by adding -s even if the y is preceded by a consonant.
Singular Plural Murphy Murphys
Nouns ending in s, ss, sh, ch, x, or z form their plurals by adding -es.
Singular Plural boss bosses
Nouns ending in y. Nouns ending in y preceded by a vowel form their plurals by adding -s.
Singular Plural boy boys
Regular plurals. Most nouns form their plurals by adding -s.
Singular Plural cat cats
Words ending in the /k/ sound which is spelled ch add -s:
Singular Plural monarch monarchs
To show separate ownership, add the possessive form to both nouns.
John's and Joe's books were on their desks-
If the singular form of the word ends in s, add an apostrophe and another s to form the possessive. Note: You will encounter singular possessives that end in s that do not include the second s, especially if the next word begins with s.
Lois's book